1. Field of the Invention
This invention relates to pyrotechnic compositions and especially such compositions which are useful in inflating an inflatable automobile safety restraint, as well as to methods for so inflating the restraint.
2. Description of the Prior Art
Various pyrotechnic formulations have been proposed for generating a gas upon combustion in order to inflate an air bag or similar safety restraint in a vehicle so as to restrain movement of an occupant in the event of a sudden deceleration of the vehicle, such as caused by a collision. Exemplary of the many patents issued in this area are the following U.S. Patents: No. 3,785,149 to Timmerman; No. 3,897,285 to Hamilton et al.; No. 3,901,747 and No. 3,912,562 to Garner; No. 3,950,009 to Hamilton and No. 3,964,255 to Catanzarite.
In order to be employed as a pyrotechnic gas generating composition for inflatable occupant restraints, several criteria must be met. The pyrotechnic must be capable of producing non-toxic, non-flammable and essentially smokeless gases over a wide range of temperatures and other environmental conditions. The gases that are generated must be at a sufficiently low temperature so as not to destroy the restraint or injure the occupant. The pyrotechnic must be safe to handle, preferably with very low or no toxicity and must be capable of generating a substantial amount of gas within a very short period of time, e.g., less than about 100 milliseconds.
The present leading candidates for commercialization in an all-pyrotechnic inflation system are sodium azide-based compositions. Such compositions exhibit excellent gas generating properties and produce a gas which consists almost totally of non-toxic nitrogen gas. However, there has been some concern raised respecting the safe handling of sodium azide. It would be desirable to provide a pyrotechnic composition and method of inflating an air bag or the like which exhibited gas generating properties akin to sodium azide but which is relatively non-toxic. It would also be desirable to provide a composition and method in which all of the above criteria are maximized.